Purpose: Cranial irradiation has been widely used in order to prevent central nervous system (CNS) relapse of acute lymphoblastic leukemia (ALL) in childhood. Owing to the risk of late side effects, the Nordic Society for Pediatric Hematology and Oncology (NOPHO) replaced CNS irradiation with systemic high-dose methotrexate (HDMTX) in 1992. A prospective study of the effects of HDMTX and intrathecal MTX on CNS function is in progress at our center.
Patients and methods: Six ALL patients underwent (99m)Tc-HMPAO single-photon emission computed tomography (SPECT) examination of regional cerebral blood flow (rCBF): three owing to neurological symptoms during treatment for ALL and the other three as part of the study.
Results: All the patients had various degrees of disturbed rCBF, which was more pronounced in the patients with neurological symptoms. One patient had severe symptoms and impaired rCBF after three intrathecal injections of MTX but before administration of HDMTX.
Conclusions: Impaired cerebral perfusion was found in patients with and without neurological symptoms during treatment for ALL. The impact of these findings is still unknown, from both the long- and the short-term perspective. The possibility that intrathecal MTX alone or in combination with HDMTX may affect rCBF through vascular damage should be further investigated, in terms of both mechanisms and clinical significance.